Do email for at least 15 mins
If you check email, set aside at MINIMUM 15 minutes to work on it. The goal is to train our brain and ourselves to work on a SINGLE task for a longer period of time. This increases focus and concentration. At work, I currently have my mail program check for new mail every 45 minutes. On my personal email, I check maybe 2-3 times a day (morning, lunch, evening).
For me, I am loving the Pomodoro Technique which advocates doing a single tasks for 25 mins with 5 min breaks in between. It's gotten to the point that my coworkers know about this and will think twice before interrupting me when I have my headphones on (listening to the ticking sound on the FocusBooster app).